Method for recording a magnetic resonance image dataset, data medium, computer program product, and magnetic resonance installation

Abstract

A method for recording a magnetic resonance image dataset includes providing a magnetic resonance sequence with a series of sequence blocks, and providing at least one correction term to compensate for a magnetic field change. The magnetic field change is produced as a change of an actual magnetic field compared to a setpoint magnetic field by gradient pulses. The magnetic field change is established via a transfer characteristic of the gradient system of the magnetic resonance installation. The at least one correction term is used to compensate for the magnetic field change, and at least one magnetic resonance image dataset is recorded with the magnetic resonance sequence using the correction term.

The invention claimed is: 
     
       1. A method for recording a magnetic resonance image dataset with a magnetic resonance installation having a gradient system, the method comprising:
 providing a magnetic resonance sequence for carrying out a magnetic resonance measurement, wherein the magnetic resonance sequence has a series of sequence blocks and an excitation section, and at least one detection section is present in each sequence block of the series of sequence blocks, and wherein the magnetic resonance sequence has at least one gradient pulse; 
 providing at least one correction term to compensate for a magnetic field change, wherein the magnetic field change is produced as a change of an actual magnetic field compared to a setpoint magnetic field by the at least one gradient pulses, wherein the magnetic field change is established via a transfer characteristic of the gradient system of the magnetic resonance installation, and the transfer characteristic represents the system characteristic of the gradient system in amplitude, phase, or amplitude and phase of different frequencies; 
 compensating for the magnetic field change using the at least one correction term; 
 recording, using the magnetic resonance installation, at least one magnetic resonance image dataset with the magnetic resonance sequence using the at least one correction term; and 
 compensating for deviations of the at least one gradient pulse using a transfer characteristic-based pre-emphasis filter for the gradient system, the magnetic resonance installation comprising the transfer characteristic-based pre-emphasis filter for the gradient system. 
 
     
     
       2. The method of  claim 1 , wherein a Steady State Free Precession (SSFP) measurement sequence is used as the magnetic resonance sequence. 
     
     
       3. The method of  claim 1 , further comprising creating a compensation field using the at least one correction term,
 wherein the compensation field is applied at least in part after at least one detection section of the magnetic resonance sequence. 
 
     
     
       4. The method of  claim 1 , wherein the magnetic field change is a magnetic field change of the basic magnetic field, and the correction term is used to create a compensation phase or a basic compensation field. 
     
     
       5. The method of  claim 4 , wherein the magnetic field change of the basic magnetic field is computed as:
   Δ B   k,l=0 ( t )=ℑ 1 (ℑ{Gnom, k ( t )}·GSTFk, l ( f )}),
 
 wherein l refers to the 0th order of a transfer function of the gradient system of the magnetic resonance installation, k refers to a gradient axis, ℑ refers to a Fourier transform, and G nom,k  refers to the at least one gradient pulse applied to the gradient axis. 
 
     
     
       6. The method of  claim 1 , wherein the magnetic field change is a magnetic field change of the at least one gradient pulse, and the correction term is used to create a compensation gradient moment. 
     
     
       7. The method of  claim 6 , further comprising storing the correction term for the compensation moment in a pre-emphasis filter for the gradient system of the magnetic resonance installation. 
     
     
       8. The method of  claim 7 , wherein the pre-emphasis filter is used exclusively for correction of the magnetic field change of the at least one gradient pulse. 
     
     
       9. The method of  claim 6 , further comprising adding the compensation gradient moment to a gradient pulse after the setting of parameters of the magnetic resonance sequence. 
     
     
       10. The method of  claim 1 , wherein the magnetic field change is a magnetic field change of a field term of an order greater than 1, and the correction term is determined to create a compensation field moment. 
     
     
       11. The method of  claim 1 , wherein a transfer function or a Fourier-transform of the transfer function is used as the transfer characteristic. 
     
     
       12. A non-transitory computer-readable storage medium that stores instructions executable by a control facility to record a magnetic resonance image dataset with a magnetic resonance installation having a gradient system, the instructions comprising:
 providing a magnetic resonance sequence for carrying out a magnetic resonance measurement, wherein the magnetic resonance sequence has a series of sequence blocks and an excitation section, and at least one detection section is present in each sequence block of the series of sequence blocks, and wherein the magnetic resonance sequence has at least one gradient pulse; 
 providing at least one correction term to compensate for a magnetic field change, wherein the magnetic field change is produced as a change of an actual magnetic field compared to a setpoint magnetic field by the at least one gradient pulse, wherein the magnetic field change is established via a transfer characteristic of the gradient system of the magnetic resonance installation, and the transfer characteristic represents the system characteristic of the gradient system in amplitude, phase, or amplitude and phase of different frequencies, and wherein the magnetic field change is a magnetic field change of the at least one gradient pulse, and the at least one correction term is used to create a compensation gradient moment; 
 compensating for the magnetic field change using the at least one correction term; 
 recording, using the magnetic resonance installation, at least one magnetic resonance image dataset with the magnetic resonance sequence using the at least one correction term; and 
 storing the at least one correction term for the compensation moment in a pre-emphasis filter for the gradient system of the magnetic resonance installation, 
 wherein the pre-emphasis filter is used exclusively for correction of the magnetic field change of the at least one gradient pulse. 
 
     
     
       13. The non-transitory computer-readable storage medium of  claim 12 , wherein a Steady State Free Precession (SSFP) measurement sequence is used as the magnetic resonance sequence. 
     
     
       14. The non-transitory computer-readable storage medium of  claim 12 , wherein the instructions further comprise creating a compensation field using the at least one correction term, and
 wherein the compensation field is applied at least in part after at least one detection section of the magnetic resonance sequence. 
 
     
     
       15. The non-transitory computer-readable storage medium of  claim 12 , wherein the magnetic field change is a magnetic field change of the basic magnetic field, and the correction term is used to create a compensation phase or a basic compensation field. 
     
     
       16. A magnetic resonance installation comprising:
 a gradient system; and 
 a control facility, 
 wherein the control facility is configured to record a magnetic resonance image dataset with a magnetic resonance installation having a gradient system, the recordation of the magnetic resonance image dataset comprising:
 provision of a magnetic resonance sequence for carrying out a magnetic resonance measurement, wherein the magnetic resonance sequence has a series of sequence blocks and an excitation section, and at least one detection section is present in each sequence block of the series of sequence blocks, and wherein the magnetic resonance sequence has at least one gradient pulse; 
 provision of at least one correction term to compensate for a magnetic field change, wherein the magnetic field change is produced as a change of an actual magnetic field compared to a setpoint magnetic field by the at least one gradient pulses, wherein the magnetic field change is established via a transfer characteristic of the gradient system of the magnetic resonance installation, and the transfer characteristic represents the system characteristic of the gradient system in amplitude, phase, or amplitude and phase of different frequencies; 
 compensation for the magnetic field change using the at least one correction term; and 
 recordation, by the magnetic resonance installation, of at least one magnetic resonance image dataset with the magnetic resonance sequence using the at least one correction term, 
 
 wherein the magnetic resonance installation further comprises a transfer characteristic-based pre-emphasis filter for the gradient system, and the transfer characteristic-based pre-emphasis filter is used to compensate for deviations of the at least one gradient pulse. 
 
     
     
       17. A method for recording a magnetic resonance image dataset with a magnetic resonance installation having a gradient system, the method comprising:
 providing a magnetic resonance sequence for carrying out a magnetic resonance measurement, wherein the magnetic resonance sequence has a series of sequence blocks and an excitation section, and at least one detection section is present in each sequence block of the series of sequence blocks, and wherein the magnetic resonance sequence has at least one gradient pulse; 
 providing at least one correction term to compensate for a magnetic field change, wherein the magnetic field change is produced as a change of an actual magnetic field compared to a setpoint magnetic field by the at least one gradient pulses, wherein the magnetic field change is established via a transfer characteristic of the gradient system of the magnetic resonance installation, and the transfer characteristic represents the system characteristic of the gradient system in amplitude, phase, or amplitude and phase of different frequencies; 
 compensating for the magnetic field change using the at least one correction term; and 
 recording, using the magnetic resonance installation, at least one magnetic resonance image dataset with the magnetic resonance sequence using the at least one correction term, 
 wherein the magnetic field change is a magnetic field change of a basic magnetic field, and the at least one correction term is used to create a compensation phase or a basic compensation field, 
 wherein the magnetic field change of the basic magnetic field is computed as:
   Δ B   k,l=0 =( t )=æ 1 {Gnom, k ( t )}·GSTFk, l ( f )}), and
 
 
 wherein l refers to the 0th order of a transfer function of the gradient system of the magnetic resonance installation, k refers to a gradient axis, æ refers to a Fourier transform, and Gnom,k refers to the at least one gradient pulse applied to the gradient axis. 
 
     
     
       18. A method for recording a magnetic resonance image dataset with a magnetic resonance installation having a gradient system, the method comprising:
 providing a magnetic resonance sequence for carrying out a magnetic resonance measurement, wherein the magnetic resonance sequence has a series of sequence blocks and an excitation section, and at least one detection section is present in each sequence block of the series of sequence blocks, and wherein the magnetic resonance sequence has at least one gradient pulse; 
 providing at least one correction term to compensate for a magnetic field change, wherein the magnetic field change is produced as a change of an actual magnetic field compared to a setpoint magnetic field by the at least one gradient pulses, wherein the magnetic field change is established via a transfer characteristic of the gradient system of the magnetic resonance installation, and the transfer characteristic represents the system characteristic of the gradient system in amplitude, phase, or amplitude and phase of different frequencies, and wherein the magnetic field change is a magnetic field change of the at least one gradient pulse, and the at least one correction term is used to create a compensation gradient moment; 
 storing the at least one correction term for the compensation moment in a pre-emphasis filter for the gradient system of the magnetic resonance installation, 
 compensating for the magnetic field change using the at least one correction term; 
 recording, using the magnetic resonance installation, at least one magnetic resonance image dataset with the magnetic resonance sequence using the at least one correction term, 
 wherein the pre-emphasis filter is used exclusively for correction of the magnetic field change of the at least one gradient pulse.